Low-power laser diode (LD) systems, i.e. those that employ LDs configured to generate light output in the range of milliWatts, generally utilize LDs having small-size active regions or cores. The small dimensions of an active region of such LD are chosen intentionally, to ensure that the light output from such laser contains only one spatial mode (typically, the lowest spatial mode) to facilitate further processing of the laser beam such as, for example, to simplify the process of coupling of the laser output into a single-mode optical fiber or waveguide. A LD with a small active region is known to suffer from heating issues (often resulting in material thermal damage) when the operation of such LD is scaled up to satisfy a need in high output power. At the same time, the use of LD chips with spatially large active regions or cores, which structurally are capable of generating high output optical power is generally ruled out because, understandably, LDs with active region waveguides that are sufficiently large support spatially-multimode operation, which is not desirable from the point of view of efficient utilization of the laser output. As a result, a high power LD system is typically structured as an array of laser sources containing small-core emitter arrays, which is known as a diode bar or stack. The array is typically designed such that individual optical fields generated by the individual emitter-components of the array are coupled to form a total optical field characterized both by high power and desired beam quality.
There remains a need for a laser diode system that utilizes output power advantages provided by a LD with a large active region but yet maintains the desired quality of the output beam.